The present invention relates to electrical separable connector modules for connecting together the operating components of an underground power distribution system by means of shielded electrical cable.
Separable connector assemblies for underground power distribution cable, or shielded cable, are watertight when assembled and may be readily separated into two or more units to break a cable connection. As such units are available separately commercially for various reasons and are individually subject to special design considerations, they are commonly referred to as "modules". Thus, a connection includes two or more matching modules assembled together.
One type of separable connector commonly used is known as a "rod and bore" type. A bore connector module having a receiving bore in a shielded, insulating housing and a grasping contact member in the bore receives a matching rod connector module having rod contact extending axially along a receiving passageway, or cone, in the rod housing for receiving the matching portion of the bore module. The rod is inserted in the bore and grasped by the bore contact member. Examples of this type of connector are described, for example, in the following U.S. Patents:
U.s. pat. No. 3,513,437 issued May 19, 1970 to W. A. Morris PA1 U.s. pat. No. 3,542,986 issued Nov. 24, 1970 to E. J. Kotski PA1 U.s. pat. No. 3,551,587 issued Dec. 29, 1970 to R. F. Propst PA1 U.s. pat. No. 3,587,035 issued June 22, 1971 to E. J. Kotski, and PA1 U.s. pat. No. 3,955,874 issued May 11, 1976 to V. J. Boliver.
A rod module generally has an elastomeric insulating housing with an outer conductive shield layer connected to ground. The housing has a cable entrance opening at one end through which a cable is electrically connected to an embedded crimp connector fixture. The fixture is surrounded by a conductive shielding insert layer of elastomer for assuring that there are no voids between the conductive internal components and the insulating housing material. The housing is additionally provided at another end with an elongated passageway extending from an open exterior end toward the fixture. A conductive contact rod is fixed at one end to the crimp fixture and extends along the axis of the passageway. The configuration of the passageway is that of a truncated circular cone segment tapering in toward the insert and therefore the passageway is commonly referred to as the "cone". The cone is adapted to receive a bore module housing portion of matched configuration with a receiving bore for guiding the contact rod to a set of female contacts. The exterior end of the well may additionally be provided with a short skirt of elastomer to prevent restrike to the ground shield through ionized gases generated by arcing in the bore when energized modules are disconnected.
It has been found that when such rod modules as described above are used for disconnecting energized cable of relatively high distribution voltages, such as, for example, 12 kilovolts and higher, an audible corona can arise inside the cone of the rod module after disconnection. This corona will in some cases result in a dielectric breakdown of the arc-generated gases in the cone and cause the rod contact to be short circuited to the grounded shield of the housing or other adjacent grounded surfaces.